As control measures against malaria, my laboratory has focused on the interruption of sporogonic development of the parasite in the mosquito. The fact that most mosquitoes, other than a few Anopheline mosquitoes, are refractory to human malaria transmission suggests that blockades to Plasmodium development do exist in mosquitoes, and it will be useful to understand the nature of this blockade to reduce the transmission of malaria. The initial successes of transmission-blocking vaccines using antigens specific to mosquito stage of the parasite have demonstrated the potential of this approach. The major projects in this program can be classified under, the study of Plasmodium in mosquitoes. I. Mosquito midgut epithelium invasion by ookinete II. Ookinete adhesion to mosquito midgut epithelium III. Characterization of soluble mosquito factors that influence parasite development IV. Characterization of novel oocyst-specific molecules